Symptom of an organization that doesn't plan and instead of budgeting for 1.3x employees for outside hours support, budgets for ~0.9x and extracts the rest with "expectation".
So...definitely for larger orgs, where "emergency availability" would be a big red flag, unless one explicitly opted into a (compensated) on call rota.
I guess one can make an exception for very early career, but again this was about setting a 9-5 boundary